Shotgun.



ccLUMBlA PLANOGRAPH ED..WASHINGTDN. D. c.

rarnivr eserciti.

FRANK F. BURTON, OF EAST HAVEN, CONNECTICUT, ASSIGNOR TO VINCHESTERREPEATING ARMS CO., OF NEW HAVEN, CONNECTICUT, A CORPORATION.

SHOTGUN.

Loeaaso.

To all whom t may concern Be it known that I, FRANK F. BURTON, a citizenof the United States, residing at East- Haven, in the county of NewHaven and State of Connecticut, have invented a new and usefulImprovementI in Shotguns; and I do hereby declare the following, whentaken in connection with the accompanying drawings and the characters ofreference marked thereon, to be a full, clear, and eX- act descriptionorn the same, and which said drawings constitute part of thisapplication, and represent, in

Figure l a broken view partly in elevation, and partly in longitudinalsection of a shot-gun barrel constructed in accordance with myinvention. Fig. 2 a similar view showing a paper-shell cartridge inposition in the barrel. Fig. 3 a detached view in side elevation ot apaper-shell cartridge. Fig. et a. view corresponding to Fig. 1, butshowing the cartridge-chamber of the barrel treated throughout itslength in accordance with my invention. Fig. 5 is a broken view, greatlyenlarged, of a portion of such a nurling tool as may be employed inpractising my invention. Fig. 6 a sectional view on the line a-Z) ofFig. 5. Fig. 7 a broken view, greatly enlarged, showing a portion of thesurface produced upon the interior walls of the cartridge-chamber by theaction of the nurl. Fig. 8 a broken perspective view of Fig. 7.

YVhen paper-shell cartridges were :lirst invented and put upon themarket only black powders were in use. 0n ignition these powders producerelatively low pressures and consequently cut-offs, so called, were sorare as to be practically negligible. By cut-offs7 I mean the shearingof the paper tube of a paper-shell cartridge from the sheet-metal cap ofthe shell along the line of the edge of the cap where the paper andmetal come together. lWhen a cut-0E occurs the sheet-metal cap isextracted in the usual manner, but the largest portion ot the tuberemains, stuck in the cartridgechamber of the gun-barrel and can be eX-tracted only with diiiiculty and often not without the expenditure ofprecious time. Frequently the tube lett in the cartridgechamber is sofirmly adhered to the walls thereof that it can be removed only by ahook. With the advent or" smokeless powders which produce higherpressures than Specicaton of Letters Patent.

Application filed March 21, 1912.

Patented June d, 19112. serial no. 685,346.

black powders, cut-oifs became so frequent as to be a source of greatannoyance. Consequently the problem of avoiding cut-otts became one ofthe most serious problems connected with the manufacture and use of whatthe trade knows as paper shell ammunition. A variety of expedients wereresorted to for the correction of this diiiiculty. None of them havebeen more than measurably successful; some of them have been attendedwith considerable eXtra eX- pense; all of them have attempted to solvethe problem by some modification of the shells themselves.

The object of my invention is to prevent cut-Otis, not by changing theAconstruction of paper-shell cartridges, but by modifying theconstruction of the gun barrel itself.

With these ends in view, my invention consists in a gun having the wallsof the cartridge-chamber of its gun-barrel formed with a plurality ofanchoring-pockets to anchor the sheet-metal caps of paper-shellcartridges at the instant of tiring to prevent the said caps againstlongitudinal rearward movement and separation from the paper tubes ofthe shells.

In carrying out my invention as herein shown, the rear portion of theinterior walls of the cartridge-chamber 2 of the gun-barrel 3 aresubjected to a nurling or swaging or other equivalent forming operationfor the production of a gripping surface consisting of a great number ofregularly arranged tapering anchoring pockets d isolated from each otherby ridges 5 intersecting each other at or about right angles. Thepockets 4 may be varied in depth, in specilic form and amount ofseparation from each other, all depending upon the particular characterof t-he tool used to produce them upon the highly polished rear portionsof the walls of the cartridge-chamber; but whatever their specific shapeand arrangement, and number, and however produced, they must be adapted,in order to function in accordance with my invention, to sufiicientlyreceive portions of the sheet-metal cap 6 of a paper-shell cartridge inthe chamber 2, to anchor the said cap 6 and rmly hold it againstlongitudinal movement rearward, whereby the cap is prevented from beingtorn away from the projecting portion of the paper tube 7, along theedge 8 forming the mouth of the cap, it being understood that thepressures produced by the firing of the cartridge operate to instantlyforce portions of the cap into the anchoring pockets 4 formed in thewalls of theV cartridgecliainber as described. 1 may further say thatthe high pressures produced by smokeless powders at the time of ignitionand eX- plosioii expand both the sheet-metal cap G and the paper-tube Tof the cartridge and force their exterior surfaces into intimate contactwith the inner surfaces of the cartridge-chamber 2. These high pressuresalso tend to force the sheet-metal cap 6 of the cartridge rearward, andunless this tendency of the cap to be moved rearward is effectuallyresisted, the cap will move rearward and be torn away from thepaper-tube T along the edge 8 of the cap. In short a cutoff will result.The cap will then be free to be extracted as usual, but the tube will beleft in the cartridge-chamber 2 to be extracted by itself by such meansas the user of the arm can devise. I should also explain in thisconnection that the breech-closures of the guns in which paper-shellammunition is used may be slightly opened before the pressures haveentirely expended themselves. It is this remaining pressure tending topush the cap G rearward that, generally7 speaking, tears the metal capaway from the paper tube. By providing the cartridge-chamber 2 with asufficient number of anchoring pockets 4, as described. I ani able toanchor the cap at the time of firing and so entirely control theposition of the cap at the time of firing and until after the pressureshave spent themselves.

1n the gun-barrel shown in Figs. 1 and 2 of the drawings, the interiorwalls of the cartridge-chamber 2 are lled, so to speak, with anchoringpockets 4 from the rear end of the chamber 2 forward for a distanceapproximately corresponding to the length of the longest metal caps usedin this class of cartridges, which, as is well known, have metal capsvarying in length according to the load. By extending the pitted surfacefar enough forward to cover the longest metal caps used, the gun will beadapted to prevent cut-offs in the use of paper-shell cartridges havingmetal caps from the shortest to the longest. The cartridge shown in Fig.3 has a metal cap 6 of the maximum length. 1f desired, the pitting ofthe interior walls of the cartridge-chamber of a gun constructed inaccordance with my invention, may be carried forward of the pointindicated by metal caps of maximum length even to the forward end of thepaper tube, as shown by Fig. e, in which the cartridge-ehamber 9 of thegun-barrel 12 has its walls provided with pockets 13 throughout theentire length of the chamber, but I have found that the provision of therear portion of the cartridge-chamber with pockets of the characterdescribed, effectually prevents the rearward movement of the caps at thetime of firing, and meets all of the requirements of avoiding what areknown to shooters as cut-offs.

1n Figs. 5 and 6 I have shown enlarged views of portions of such a nurlor swaging tool l-Lt as might be used in practising my invention. Itwill be seen that itis the cameo of which the surface produced by it isthe intaglio.

I claim A gun having the walls of the cartridgechaniber of itsgun-barrel formed with a plurality of anchoring-pockets to anchor thesheet-metal caps of paper-shell cartridges atV the instant of firing toprevent the said caps from longitudinal rearward movement and separationfrom the paper tubes of the shells.

1n testimony whereof, I have signed this specification in the presenceof two subscribing witnesses.

FRANK F. BURTON. `Witnesses:

Dimmi. H. VEADER,

F RANK A. PAUL.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

